A low-noise amplifier (LNA) and a wave detector are included in a monolithic microwave integrated circuit (MMIC), which is used for detecting a weak high-frequency signal in a millimeter wave region. A backward diode is sometimes used as the wave detector. A backward diode is possible to sharpen rising of current compared to a Schottky diode.
However, there is a problem in which it is difficult to obtain a mesa structure stably in a conventional backward diode. Namely, it is difficult to obtain sufficient reproducibility and reliability. The problem as stated above may occur in a pn junction diode.
[Patent Document 1] Japanese Laid-open Patent Publication No. 2010-251689
[Patent Document 2] Japanese Laid-open Patent Publication No. 2005-328036
[Patent Document 3] Japanese Laid-open Patent Publication No. 08-8418
[Patent Document 4] Japanese Laid-open Patent Publication No. 2012-43965